Helical draft rolls



March 28, 1967 g, w, u c 3,310,847

LICAL DR Filed June 9, 1964 United States Patent 3,310,847 HELECAL DRAFT ROLLS Christoph W. Aurich, Clemson, S.C., assignor to Marernout Corporation, Chicago, Ill., a corporation of Illinois Filed June 9, 1964, Ser. No. 373,793 1 Claim. (Cl. 19258) The present invention relates to drawing frames of the type commonly used in the manufacture of cotton yarn in doubling and drawing strands of roving or sliver.

The drawing frame comprises generally a series of pairs of intermeshing rolls positioned one in advance of another through which the web composed of rovings is fed, each successive pair of rolls being driven at a slightly higher peripheral speed than the preceding pair so as to produce a desired draft.

For maximum drafting efliciency, drafting rolls have been constructed with resilient or cotted surfaces and are carefully weighted to provide a soft nip to avoid crushing or breaking of the delicate cotton fibers. In some instances hard surface rolls are employed, which may be smooth-faced, or fluted as illustrated in the US. patent to Tarr, No. 2,398,756, for Textile Drawing Frame, dated Apr. 16, 1946. Such rolls have been employed in various combinations. Drafting rolls of the general type above referred to have, however, been found unsatisfactory for operation at the very high speeds required of modern textile machinery. At these speeds top rolls employing resilient cots tend -to deflect somewhat which results in excessive heating causing cot damage and extreme wear. Drafting speeds with hard suface rolls have heretofore been severely restricted by the tendency to poor drafting feed control, and also where fluted rolls are employed, by the tendency to overheating and disintegration of the fibers which results from the harsh handling and violent flexing of the fiber mass at such speeds.

It is a principal object of the invention to provide an improved construction and arrangement of cooperating drafting rolls of a drafting frame in which hard surface helically fluted drafting rolls are provided, formed and arranged in such a manner as to permit substantially higher linear traveling speeds to be employed without any tendency to overheating, disintegration or weakening of the fiber, and further without subjecting the rolls to excessive wear.

In accordance with this object the hard surface exterior of each roll is formed with flutes having gently sloping flanks disposed with relation to each other at a greater than 90 included angle, with rounded top and valley portions formed on radii of substantial lengths providing a substantially continuous rolling nip between the opposed surfaces of the roll betweensaid blanks and, also between opposed top and valley portions of said surfaces. These flutes are formed with a helix angle, which may as shown he in the order of 3 and which has been found essential for eflicient operation of the fluted rolls. In addition to the usual advantages of quiet operation inherent in helically formed gearing, the plurality of simultaneously engaged longitudinally traveling nips between adjacent pairs of opposed flutes of applicants drafting rolls provides for a firm control of the relative rotational positions of the two rolls of the pair which would normally be considered possible only with flutes having more steeply inclined flanks. A rolling nip is applied to the engaged fiber mass in which both the drafting tension applied tangentially, and radially exerted pressures against the feeding fiber mass are maintained at substantially constant values.

It is a further object of the invention to provide fluted drafting rollers of improved construction adapted for the performance of a combined drafting and crushing operation, the hard surfaced fluted rollers illustrated being so formed as to provide the necessary fiber control or grip for accurate drafting, while at the same time a substantially continuous rolling engagement of the fluted surfaces under high pressure is maintained to effect the crushing operation.

The nature of the invention will be readily understood from the following description when read in connection with the accompanying drawing, and the novel features will be particularly pointed out in the appended claims. In the drawing:

FIG. 1 is a somewhat diagrammatic vertical sectional view of a drawing frame with some parts shown in elevation;

FIG. 2 is an enlarged sectional view of small cooperating portions of the back line pair of drafting rolls illus trated in FIG. 1;

FIG. 3 is an enlarged sectional view of small cooperating portions of the front line pair of rolls illustrated in FIG. 1 adapted for carrying out a combined drafting and crushing operation on the fiber mass; and

FIG. 4 is a detail view in elevation illustrating a pair of fluted drafting rolls in accordance with the invention.

Referring first to FIG. 1, the construction there shown comprises four pairs of metallic intermeshing rolls including bottom rolls 10, 12, 14, 16 and top rolls cooperating with the respective bottom rolls and indicated at 18, 2t), 22, 24. The bottom rolls are positively driven by gearing, not shown, while the top rolls are driven entirely by their relationship to the bottom rolls and through the intervening fiber or stock W. The top rolls 18, 20, 22, 24 are provided with gudgeons carried in adjustable bearings which are biased downwardly to provide the necessary pressure between the rolls of adjacent pairs. The biasing mechanism as shown in FIG. 1 comprises a pair of horizontally disposed bars 26, one being disposed at each side of the machine overlying the gudgeons formed on the ends of the respective top rolls. Each of the bars 26, one of which is shown in FIG. 1, carries four pressure cylinders 28, 3th, 32, 34 having plungers 35 which may, for example, be loaded by springs 36, and which bear against the gudgeons of the respective top rolls 1824, inclusive. Each bar 26 is supported at one end on a fixed pivot 38, and at its other end is connected to a cam actuated link 40 arranged to be tightened by a manually operated lever 42 and rotatable cam 44. The pressures at which the respective upper rolls are biased toward the mating lower rolls may be adjustably determined by adjustment of the loading springs 36, housed in the respective pressure cylinders 2834 for biasing downwardly the associated plungers 35. Each successive pair of rolls proceeding from right to left is driven at a sufiiciently higher speed than the preceding pair to produce the desired draft which in the present instance is assumed to be a standard 9.5 ratio.

So far as the general organization of the construction just described is concerned, it may be exactly like those in common use, and it may be equipped with the usual guides, stop devices, and other accessories normally used in drawing frames. A customary arrangement is to draw the strands of roving or sliver from supply cans set up at the right hand side of the machine, to feed them together in the form of a web W through the rolls, and then to guide the reduced 'we'b issuing from the front or delivery rolls 10 and 18 into the trumpet of a coiler which deposits the drawn strand in a roving can.

While applicants helically fluted drafting rolls are here shown as weighted in a conventional manner by means of pressure cylinders acting against the two ends of each upper roll, it will be understood that applicants fluted drafting roll construction may be combined advantageously with weighting devices of other types as, for example, the magnetic weighting device described in applicants copending application Ser. No. 226,936, filed Sept. 28, 1962, now Patent No. 3,150,419, for Magnetic Drafting Roll with Steel Sleeve, whereby the even weighting of the rolls of each pair along their length is doubly assured.

In accordance with the invention the drafting rolls are formed of a hard surface material, preferably metallic although other hard surface materials may be employed, which is fluted in a novel manner to maintain the firm grip upon the fiber which is necessary for high-speed operation without at the same time subjecting the fiber to the highly injurious beating and rapid flexing action produced by the operation of fluted drafting rolls found in the prior art at said high speeds.

As best shown in FIG. 3 of the drawing the front line pair of rolls 10 and 13 are identically formed, one flute 45 being allocated to each 10 of circumference of the drafting roll which by way of illustration is assumed to have a pitch line radius of .6250", and an outside circumference radius of .010 greater and a root radius of .012"

less than the pitch radius. The flute top radius is .0328" and the valley radius is .0344". It will be understood that the particular roll dimensions above noted are by way of illustration only, and that certain of these dimensions as, for example, the 10 circumference per flute and the pitch line radius, will obviously vary as the diameter of any particular roll is varied. The flanks 46 of the flutes as shown in FIG. 3 are set with relation to one another at a substantially greater than 90 included angle. The tops and adjacent valley portions 47 of the flutes are formed on large radii whereby the configuration achieved is a gently undulating surface having formed therein moderate bends which provide a minimum crimp-ing effect upon the fibers engaged thereby. As will be noted from an inspection of FIG. 3, the flutes 45 on each of the two rolls 10 and 18 are similarly formed, and the contours are so chosen that a substantially continuous rolling nip of the processed material or fiber mass W between said rolls is maintained in which the opposed surfaces of the nip are held at a substantially uniform distance from one another while the nip travels from the tip of each flute along the flank inwardly to the valley portion thereof, thence along the flank of the next succeeding flute to the tip of said second flute. A relatively easy undulating motion is thus imparted to the feeding fiber mass which has a minimum tendency to produce heating, disintegration or separation of the fibers when the rolls are driven at high linear speeds which may be in the order of 1500' to 2000 or more per minute.

The flutes of the illustrated drafting rolls are given a helix angle of 3% which is of opposite hand in the upper and lower rolls as shown in FIG. 4 to produce a con tinuously traveling nip lengthwise of said rolls.

The illustrated construction differs in important respects from ordinary gearing in which the gears are formed with involute curves, and also from fluted drafting rolls of the prior art in which the rolls are related to one another by means of a nip against adjacent steeply inclined flank portions of the flutes only. The helical arrangement of applicants gently sloped flutes has the advantage that a plurality of nips, for example, four such nips, are established 'and are maintained simultaneously between different opposed pairs of flutes along the length of the rolls. Stresses set up tangentially of the drafting rolls through the nip by the drafting differentials are thus distributed over the four nips, so that the upper and lower drafting rolls are maintained in their correct operating positions with no tendency of the gently sloped flanks to pinch the fiber mass. With the illustrated construction similar traveling nips are maintained between the top portions of the respective flutes and the opposed valleys formed between the flutes of the opposite roll which assist materially to maintain the upper and lower rolls in the correct angular relationship, and also to secure a firm drafting grip upon the advancing fiber web or mass.

The use of the helix angle when thus combined with the gently sloped flutes acts to maintain the substantially continuous rolling nip herein referred to.

The back line pair of drafting rolls 16 and 24 are provided with flutes 50 different in certain respects from the flutes of the front line rolls 10, 18 above described (see- FIG. 2). Each flute 50 is formed with flanks 52 sloped. with relation to one another at a substantially greater than 90 included angle. The tips of the flutes 50 are, however, deeper and more pointed than the valleys in order to obtain a firm grip on the relatively thick mass. of fiber drawn into the drafting frame. In this respect it may be noted that the bottom and top radii of the fluting; is related to the thickness or bulk of stock processed by the rolls. The difference between the valley radius and the top radius of each flute corresponds approximately to the bulk thickness of the fiber mass W being processed. Referring specifically to FIG. 2, the radius of the outer diameter tip of the flute is .010" Whereas the radius of' the valley portion is .025". The difference in radius is. .015". The difference in the valley and flute radii for the front line rolls 10, 18 is only .0016". As can be seen from these figures the ratio between these differences in tooth radii corresponds also to the approximate draft ratio. In the illustration given the draft ratio between the back rolls 16, 24 and the front rolls 10, 18 is assumed to be a standard amount, for example, 9.5, the draft between each pair of rolls and the next being a proportional part of this amount.

The relationship of the back line rolls and fluting is as follows:

S =Sliver inch] T compressed height of 4.5 wide fiber sheet Empirical relationship T =SB/K where K:compression factor In the illustrated exampie K=2/l5 psi. and is substantially constant.

weight input=500 [grains/yd] =.002[lb./

T .0l5(inch) (measured with 80 lb. pressure applied) Fluting of back line:

Inches R =fiute valley radius (selected) .025 T .015

R =flute t-op radius .010

The relationship of the front line rolls and fluting is as follows where: D=Draft between front and back roll=9.5 S =Output sliver weight -SB/D e.g. 53 [gnainsj/ yd. TF COmPTSSEd height of 4.5" wide fiber T l" SB 2x15 l.6 (iuchl K K D 1000 2 9.5 1000 where K=2/l5 p.s.i. Fluting of front line rolls:

Inches R =fiute valley radius (selected) .0344 T .0016

R =flute top radius .0328

The fluti-ng of any intermediate pairs of rolls is readily worked out with the relationship Because the draft D gradually increases with the advance of the fibers from the back rolls to the front rolls the thickness T decreases in graduated steps and is inversely proportional to the draft between the roll considered and the back roll.

The back line draft rolls 16, 24 having the relatively pointed helical flutes 50 cooperate in the same manner as the less sharply pointed flutes shown in FIG. 2 to maintain a substantially continuous rolling nip upon the relatively bulky fiber mass W drawn between the rolls, which is adequate to insure the accurate advance of the drafted material without excessive bending or strain. The broadly sloping flanks 52 maintains a substantially continuous rolling nip upon the moving mass which varies in thickness by a minimum amount only from the nip produced by the more sharply pointed top portions of the flutes. The helix angle at which the flutes are set causes four pairs of opposed flutes to be engaged at one time, and also causes the engagement of the flutes of each pair to be transferred along the length of the rolls, thus providing a continuous even draft of the bulky fiber mass W through the back line rolls, while at the same time the yieldably supported upper back roll 24 is maintained at all times accurately in position with relation to the lower driving back roll 16.

Applicants improved helically fluted hard surface drafting rolls are particularly adapted for use as, for example, in a drawing frame of the sort here shown for the performance of a combined drafting and crushing operation. Crushing is normally effected with the use of opposed steel cylinders having smooth exterior surfaces which are forced relatively together under considerable pressure in order to apply a crushing or purifying pressure upon the web traveling therebetween. Use of such smooth faced rolls as front line rolls in a conventional drawing frame of the type shown in an effort to combine the drafting and crushing operations has been found impractical because the coefiicient of friction of such smooth surfaced rolls against the fiber mass W was insufficient to establish adequate drafting control over the fibers. With the arrangement here shown in which the front drafting rolls are provided with flutes having the construction de- 6 scribed and illustrated in effect is produced simply by increasing substantially the pressure applied by the cylinders 28 upon the upper drafting roll 18 to a point at which the pressure exerted by the top roll 1% equals that normally applied to the usual smooth faced crushing rolls. The construction of applicants front line drafting rolls 10, 18 in which similarly fluted surfaces are opposed to one another provides the necessary fiber control or grip as above set forth. These surfaces, as previously explained, also provide a continuous rolling nip between mating metallic surfaces which are capable of exerting a continuous substantially even pressure radially at the nip upon the fiber mass W passing therebetween. These two factors combine to effect a crushing operation. When adequate pressure is applied to the top front line roll 18, the front line rolls 10, 18 are found to perform in a satisfactory manner the combined drafting and crushing operation above referred to with the result that the web is purified at the same time that the drafting operation is carried out.

The invention having been described What is claimed is:

In a drawing frame a plurality of successively disposed pairs of helically fluted hard surface rolls for highspeed drafting of fibers including front line and back line pairs of said rolls in which the engaging helical fluted surfaces thereof are formed with opposed similar undulating top and valley contours which provide'a substantially continuous rolling nip, said flutes having flanks disposed at a greater than included angle, and top and valley portions formed on radii which vary in length for top and valley portions from nearly equal length for said front line pair of rolls to a ratio of radius length in which the top radius is shorter than the valley radius for said back line teeth by an increasing ratio which corresponds to the bulk thickness of the fiber mass passed through each said pair of rolls, and to the increase in draft ratio from said back line to said front line rolls.

References Cited by the Examiner UNITED STATES PATENTS 709,694 9/1902 Bietenholz 19-258 2,398,756 4/1946 Tarr 19258 2,700,253 1/1955 Courtney et al 19258 X MERVIN STEIN, Primary Examiner. D. NEWTON, P. C. FAW, Assistant Examiners,

FIG. 3, the desired crushing 

